1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!-- http://linux-ntfs.sourceforge.net/ntfs/files/bitmap.html -->
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta name="description" content="NTFS Documentation">
<link rel="stylesheet" type="text/css" href="../style/ntfsdoc.css">
<link rel="start" type="text/html" href="../index.html" title="NTFS Documentation">
<title>$Bitmap (6) - File - NTFS Documentation</title>
</head>
<body>
<table border="0" class="toolbar" summary="" cellspacing="0">
<tr>
<td class="toolbar"><a accesskey="1" class="toolbar" href="../index.html">Home</a></td>
<td class="toolbar"> </td>
<td class="toolbar"><a accesskey="2" class="toolbar" href="../files/index.html">Files</a></td>
<td class="toolbar"> </td>
<td class="toolbar"><a accesskey="3" class="toolbar" href="../attributes/index.html">Attributes</a></td>
<td class="toolbar"> </td>
<td class="toolbar"><a accesskey="4" class="toolbar" href="../concepts/index.html">Concepts</a></td>
<td class="toolbar"> </td>
<td class="toolbar"><a accesskey="5" class="toolbar" href="../help/glossary.html">Glossary</a></td>
<td class="toolbar"> </td>
<td class="toolbar"><a accesskey="6" class="toolbar" href="../help/index.html">Help</a></td>
</tr>
</table>
<h1>File - $Bitmap (6)</h1>
<a class="prevnext" accesskey="," href="dot.html">Previous</a>
<a class="prevnext" accesskey="." href="boot.html">Next</a>
<h2>Overview</h2>
<p>
This file lists which clusters are in use.
Each bit in this file represents one LCN.
</p>
<h2><a class="heading" href="../attributes/index.html">Attributes</a></h2>
<table border="1" summary="" cellspacing="0">
<tr>
<th class="numeric">Type</th>
<th>Description</th>
<th>Name</th>
</tr>
<tr>
<td class="numeric"><a class="numeric" href="../attributes/standard_information.html">0x10</a></td>
<td><a href="../attributes/standard_information.html">$STANDARD_INFORMATION</a></td>
<td> </td>
</tr>
<tr>
<td class="numeric"><a class="numeric" href="../attributes/file_name.html">0x30</a></td>
<td><a href="../attributes/file_name.html">$FILE_NAME</a></td>
<td>$Bitmap</td>
</tr>
<tr>
<td class="numeric"><a class="numeric" href="../attributes/data.html">0x80</a></td>
<td><a href="../attributes/data.html">$DATA</a></td>
<td>[Unnamed]</td>
</tr>
</table>
<h2>Layout of the File</h2>
<h3>Unnamed Data Stream</h3>
<p>The lowest bit represents the lowest numbered LCN. Thus:</p>
<table border="1" summary="" cellspacing="0">
<tr>
<th class="numeric">Bit</th>
<th class="numeric">LCN</th>
</tr>
<tr>
<td class="numeric">00000001<sub>2</sub></td>
<td class="numeric">0</td>
</tr>
<tr>
<td class="numeric">00000010<sub>2</sub></td>
<td class="numeric">1</td>
</tr>
<tr>
<td class="numeric">00000100<sub>2</sub></td>
<td class="numeric">2</td>
</tr>
<tr>
<td class="numeric">...</td>
<td class="numeric">etc</td>
</tr>
</table>
<h2>Notes</h2>
<h3>MFT Zone</h3>
<p>
To prevent the MFT becoming fragmented, Windows maintains a buffer
around it. No new files will be created in this buffer region
until the other disk space is used up. The buffer size is configurable
and can be 12.5%, 25%, 37.5% or 50% of the disk. Each time the rest
of the disk becomes full, the buffer size is halved.
</p>
<h3>Other Information</h3>
<p>
The size of this file is always a multiple of 8 bytes (64 clusters).
Because of this rounding-up, the $Bitmap will represent slightly
more clusters than the disk has. These bit are always set to 1.
</p>
<p>
The backup copy of the boot sector lies in this no-mans-land
the cluster is hence marked as in use.
</p>
<p>
In theory, on very small volume, this attribute could be resident.
In practice, Windows crashes.
</p>
<br>
<a class="contact" href="http://linux-ntfs.sourceforge.net/ntfs/files/bitmap.html">Online</a>
<!-- The two validators will only work if this page is visible on the web -->
<a class="contact" href="http://validator.w3.org/check/referer">Validate HTML</a>
<a class="contact" href="http://jigsaw.w3.org/css-validator/check/referer">Validate CSS</a>
<a class="contact" href="mailto:webmaster@flatcap.org">$Id: bitmap.html,v 1.11 2001/07/11 16:31:44 flatcap Exp $</a>
</body>
</html>
|
